[Bug]: Synchronisation error - Permission denied

[loulous24]

⚠️ Before submitting, please verify the following: ⚠️

• This is a bug, not a question or a configuration issue.
• This issue is not already reported on Github (I've searched it).
• Nextcloud Server and Desktop Client are up to date. See Server Maintenance and Release Schedule and Desktop Releases for supported versions.
• I agree to follow Nextcloud's Code of Conduct

Bug description

On Linux, when synchronising a file that has been modified by someone else and is only shared with read-only permission, the synchronisation gives an error, "permission denied".

It is because the Nextcloud client sets the permission of the file to read-only and is not able to write it again locally when it is modified.

Steps to reproduce

1. User A create a file
2. Share the file to user B with read-only permission
3. User B synchronises the file
4. Use A modifies the file
5. User B has an error "permission denied" when doing the synchronisation again.

Expected behavior

The client should set the permissions to read-write, modify the file and set again the local permissions to read-only.

Which files are affected by this bug

All files with read-only permission that are modified by someone else

Operating system

Linux

Which version of the operating system you are running.

Fedora Linux 39

Package

Appimage

Nextcloud Server version

28.0.3.2

Nextcloud Desktop Client version

3.13.0

Is this bug present after an update or on a fresh install?

Fresh desktop client install

Are you using the Nextcloud Server Encryption module?

Encryption is Disabled

Are you using an external user-backend?

• Default internal user-backend
• LDAP/ Active Directory
• SSO - SAML
• Other

Nextcloud Server logs

No response

Additional info

No response

[jstephenson]

I'm experiencing this with the current version of the desktop client (3.13.0) on Linux as well. Items are synced with read-only filesystem permissions, and the Nextcloud client is then unable to modify them as it should.